Hybrid automatic repeat request‐based intelligent reflecting surface‐assisted communication system

in Electronics Letters (2021)

The intelligent reflecting surface (IRS) is an emerging technique to extend wireless coverage. In this letter, the performance of the hybrid automatic repeat request (hybrid ARQ) for an IRS‐assisted ... [more ▼]

The intelligent reflecting surface (IRS) is an emerging technique to extend wireless coverage. In this letter, the performance of the hybrid automatic repeat request (hybrid ARQ) for an IRS‐assisted system is analysed. More specifically, the outage performance of the IRS‐aided system using hybrid ARQ protocol with chase combining is studied. The asymptotic analysis also shows that the outage performance is better and improves linearly by increasing the number of reflectors of the IRS‐aided system. The results also verify the potential of combining the ARQ scheme in the link layer of the IRS‐aided system and demonstrate that a very small change of path loss condition can impact the performance largely. [less ▲]

Impact of layer structure on performance of unpassivated AlGaN/GaN/SiC HEMTs,

in Electronics Letters (2004), 40(1), 78-80

The performance of unpassivated AlGaN=GaN=SiC HEMTs prepared on different MOVPE grown layer structures is reported. An overall improvement of device characteristics using doped structures in comparison to ... [more ▼]

The performance of unpassivated AlGaN=GaN=SiC HEMTs prepared on different MOVPE grown layer structures is reported. An overall improvement of device characteristics using doped structures in comparison to undoped counterpart is observed. This can be demonstrated by IDS of 0.86 and 1.33 A=mm, gm of 220 and 273 mS=mm, fT of 33 and 43 GHz and fmax of 54 and 61 GHz for 0.3 mm gate length devices on undoped and doped structures, respectively. The DC=pulsed I–V characteristics as well as power measurements show insignificant RF dispersion of HEMTs on doped structures. These results underline the advantage of doped layer structures for preparation of high-performance AlGaN=GaN HEMTs. [less ▲]

AlGaN/GaN HEMTs on Silicon Substrates with f¬T of 32/20 GHz and fmax of 27/22 GHz for 0.5/0.7 µm gate length,

in Electronics Letters (2002), 38(2002), 288-289

AlGaN/GaN HEMTs on silicon substrates have been realised and their static and small signal characteristics investigated. The AlGaN/GaN (x=0.23) material structures were grown on (111) p-Si by LP-MOVPE ... [more ▼]

AlGaN/GaN HEMTs on silicon substrates have been realised and their static and small signal characteristics investigated. The AlGaN/GaN (x=0.23) material structures were grown on (111) p-Si by LP-MOVPE. Devices exhibit a saturation current density of 0.53 to 0.68 A/mm and a peak extrinsic transconductance of 110 mS/mm. A unity gain frequency of 20 and 32 GHz and a maximum frequency of oscillation of 22 and 27 GHz are obtained for devices with a gate length of 0.7 and 0.5 mm, respectively. These values are the highest reported so far on AlGaN=GaN=Si HEMTs and are comparable to those known for devices using sapphire and SiC substrates. [less ▲]

AlGaN/GaN Varactor Diode for Integration in HEMT Circuits

in Electronics Letters (2001), 37(2001), 1476-1478

Fabrication and characterisation of metal-semiconductor-metal (MSM) diodes above an AlGaN/GaN HEMT layer system for varactor applications are reported. Device fabrication uses standard HEMT processing ... [more ▼]

Fabrication and characterisation of metal-semiconductor-metal (MSM) diodes above an AlGaN/GaN HEMT layer system for varactor applications are reported. Device fabrication uses standard HEMT processing steps, allowing integration in HEMT circuits without the need of sophisticated growth or etching techniques. Capacitancevoltage measurements exhibit CMAX/CMIN ratios up to 100, tunable by the electrode geometry. These results exceed best values for published heterostructure varactor diodes. Fabrication of AlGaN/GaN HEMTs on the same layer system with identical technology prove the potential for monolithic integration. [less ▲]

550 GHz bandwidth photodetector on low-temperature grown molecular-beam epitaxial GaAs

in Electronics Letters (1998), 34(1998), 119-120

The authors demonstrate that a 550GHz bandwidth photodetector can be fabricated on low-temperature grown MBE GaAs. The pulse response shows 0.4 and 0.6ps rise and fall times, respectively. The bandwidth ... [more ▼]

The authors demonstrate that a 550GHz bandwidth photodetector can be fabricated on low-temperature grown MBE GaAs. The pulse response shows 0.4 and 0.6ps rise and fall times, respectively. The bandwidth is in agreement with a value calculated using a carrier lifetime of 0.2ps, measured by femtosecond time-resolved reflectivity, and a capacitance of 0.014fF/um2, determined from microwave measurements. The device bandwidth is RC limited. [less ▲]

16 GHz Bandwidth MSM Photodetector and 45/85 GHz fT/fmax HEMT Prepared on an Identical InGaAs/InP Layer Structure

in Electronics Letters (1996), 32

Novel HEMT layout: The RoundHEMT

in Electronics Letters (1995), 31(1995), 589-591

n-InGaAs Schottky Diode with Current Transport along 2DEG Channel

in Electronics Letters (1992), 28(1992), 1689-1690

Barrier Height Enhancement of n-In0.53Ga0.47As Schottky Diodes Grown by MOCVD Technique

in Electronics Letters (1991), 27(1991), 1759-1760